Mr Abbott said his attacker "wasn't very good at it", but the blow did make contact.

"The only damage was a very, very slightly swollen lip," he said. Mr Abbott did not require medical attention.

Mr Abbott said a member of his staff who accompanied him briefly grappled with the man, before he "scarpered off, swearing".

"It was very disconcerting to find … someone who under the guise of wanting to shake your hand gives you a so-called Liverpool kiss," Mr Abbott said.

"As he was scuttling away, amidst all the F this and F that, was 'you deserve it because of all the things you've said'. I think it was pretty clear it was … politically motivated violence."

Tony Abbott tells of being assaulted by same sex marriage supporter:
Tony Abbott tells of being assaulted by same sex marriage supporter

Mr Abbott made a formal complaint about the violence after he was contacted by Tasmania Police overnight.

Officers are on the hunt for the assailant and have urged anyone who witnessed the assault, which occurred about 4.35pm on the footpath of Morrison St, opposite Customs House Hotel, to come forward.

"Police would particularly like to hear from the other man who was allegedly involved in the incident and have urged him to come forward and contact police," Tasmania Police said in a statement.

Mr Abbott has become a leading voice of the campaign against same-sex marriage leading up to the national postal survey on the issue.

The Liberal backbencher has repeatedly said in opinion pieces and on social media that same-sex marriage campaigners have been responsible for "bullying and hate speech" throughout the campaign.

Mr Abbott said today's incident was "a reminder of how ugly this debate is getting".

"The ugliness is not coming from the defenders of marriage as it's always been understood," he said.

"The love is love brigade aren't showing a lot of love."

When asked by Sky News presenter Andrew Bolt and radio host Steve Price if he had considered fighting back, the former university boxer said "the thought certainly went through my mind" but he thought better of it.

"The interesting thing about this whole debate is that it was supposed to be a trigger for bullying and intimidation and the bullying and intimidation was all supposed to come from the no side … But so far 99 per cent of the bad stuff are from the people telling us that love is love," he said.

The postal survey has sparked an outpouring of vitriol from both sides of the debate. Picture: Cameron Spencer/Getty Images.

The postal survey has sparked an outpouring of vitriol from both sides of the debate. Picture: Cameron Spencer/Getty Images.Source:Getty Images

'NEVER A PLACE FOR VIOLENCE'
Opposition leader Bill Shorten is among a group of "yes" campaigners that has condemned the violence against Mr Abbott.

Mr Shorten tweeted that he called his former political opponent to say he was pleased that Mr Abbott wasn't seriously injured.

The leader of the Australian Marriage Equality campaign, Alex Greenwich, tweeted that there was "no place for violence" in the debate.

The Equality Campaign released a statement saying it condemned the violence and there was "never a place" for abuse.

"Marriage Equality is about respect and dignity for every Australian. There is no room for any disrespect either physical or verbal in this national debate," the group said.

"Our campaign has always and will continue to call for respect and everyone involved in this debate to act in a respectful and dignified way."

Tasmanians United for Marriage Equality also said the "yes" campaign should not be judged by the actions of one person.

Spokesman Rodney Croome urged people to act with "respect and restraint" as "when this postal survey is over, we will still have to live side by side as Australians".

There is absolutely no place for violence in the marriage equality debate. This is about treating people fairly and with respect & dignity.

"This attack on Tony Abbott, like any violence on the basis of political belief, is beneath contempt and has no place in Australian public debate, especially when that debate is about love, commitment, tolerance and respect," he said, while noting other threats against "yes" campaigners from the "no" side.

Bolt, who first reported the incident, said Mr Abbott had described his alleged attacker as a having "tatts and that sort of stuff".

The presenter said Mr Abbott had told him he was "kicking himself over whether he should have punched him".

This afternoon, Mr Abbott shared pictures from a lunch in the Tasmanian capital where he had met with "no" campaigners.

It's not the first time in his political career the former PM has been assaulted.

Mr Abbott told 2GB he had been "thumped" back in about 2007 when he was health minister.

"I was actually thumped when I visited the forensic psychiatric hospital in Victoria," he said.

"One of the hospital patients punched me, as I was later told, because he was under the impression I was his dad.

"This is the first time I've been subject to any physical violence for about 10 years."

He also famously threatened to "shirt-front" Russian leader Vladimir Putin in 2014 over the downing of Malaysia Airlines flight MH17.